Chemically machined sheet metal cutting tools and method

A method of manufacturing a sheet metal tool from a metal blank of the type having a generally flat, front surface, an opposite back surface and opposing side edges, the method comprising the steps of:

• applying to the back surface of the metal blank a predetermined pattern of etching resistant material defining exposed areas separated by resist areas;
• and
• applying a layer of etching resistant material to the front surface of the metal blank which overlies the exposed areas on the back surface of the metal blank;
• subjecting the exposed areas on the back surface of the metal blank to etching treatment through the exposed areas to form a tooth shape and an associated tooth opening in each of the exposed areas, each tooth shape being formed with a cutting edge opposite a tooth base, the etching treatment being applied solely from the back surface of the metal blank, whereby the cutting edges so formed terminate in sharpened surfaces in the plane of the front surface and protected by the layer of etching resistant material on the front surface of the metal blank;
• bending at least selected teeth so formed along their respective bases to bring their respective cutting edges above the plane of the front surface of the metal blank.

A method of manufacturing a sheet metal tool from a metal blank of the type having a generally flat, front surface, an opposite back surface and opposing side edges, the method comprising the steps of:

• applying to the back surface of the metal blank a predetermined pattern of etching resistant material defining exposed areas separated by resist areas;
• and
• applying a layer of etching resistant material to the front surface of the metal blank which overlies the exposed areas on the back surface of the metal blank;
• alternating the previously described resist pattern on the front and back surfaces so that alternating exposed areas on the back surface are overlaid by a layer of resist on the front surface and so that alternating exposed areas on the front surface are overlaid by a layer of resist on the back surface;
• subjecting the exposed areas on the back surface of the metal blank to etching treatment through the exposed areas to form a tooth shape and an associated tooth opening in each of the exposed areas, each tooth shape being formed with a cutting edge opposite a tooth base, the etching treatment being applied solely from the back surface of the metal blank, whereby the cutting edges so formed terminate in sharpened surfaces in the plane of the front surface and protected by the layer of etching resistant material on the front surface of the metal blank;
• subjecting the exposed areas on the front surface of the metal blank to etching treatment through the exposed areas to form a tooth shape and an associated tooth opening in each of the exposed areas, each tooth shape being formed with a cutting edge opposite a tooth base, the etching treatment being applied solely from the front surface of the metal blank, whereby the cutting edges so formed terminate in sharpened surfaces in the plane of the back surface and protected by the layer of etching resistant material on the back surface of the metal blank;
• bending those teeth formed with their sharpened surfaces in the plane of the back surface along their respective bases to bring their respective cutting edges above the plane of the back surface of the metal blank and bending those teeth formed with their sharpened surfaces in the plane of the front surface along their respective bases to bring their respective cutting edges above the plane of the front surface of the metal blank.